26 CFR 1.643(b)-2: (b)-2 Dividends allocated to corpus.

Extraordinary dividends or taxable stock dividends which the fiduciary, acting in good faith, determines to be allocable to corpus under the terms of the governing instrument and applicable local law are not considered “income” for purposes of subpart A, B, C, or D, part I, subchapter J, chapter 1 of the Code. See section 643(a)(4), § 1.643(a)-4, § 1.643(d)-2, section 665(e), paragraph (b) of § 1.665(e)-1, and paragraph (b) of § 1.665(e)-1A for the treatment of such items in the computation of distributable net income.